There are a number of methods for characterizing crystalline structures grown on or thin films deposited on substrates, such as for example wafers made of various materials (e.g. silicon, sapphire, SiC, GaAs, InP). Many of these methods are destructive in nature, involve cutting into or etching materials from the crystalline structures or the thin films. These invasive methods may destroy the functionality of the tested structure and increase production costs and wastes. These invasive methods generally cannot be used to test every device during a manufacturing process.
Some methods are non-destructive, but they may require specialized and expensive testing equipment. For example, some methods use electromagnetic radiation (e.g. radio, UV, X-ray) to interact with the tested structures in a way allowing the tested structures to be characterized. The characterization is performed by measuring the strength of the reflection, absorption, diffraction, or polarization of the emitted radiation. Specialized equipment to generate stimulating radiation may be required.